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Philip M. Sherman - One of the best experts on this subject based on the ideXlab platform.
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Multiple seropathotypes of Verotoxin-Producing Escherichia Coli (VTEC) disrupt interferon-γ-induced tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1
Microbial Pathogenesis, 2007Co-Authors: Narveen Jandu, Mohamed A. Karmali, Songhai Shen, Mark E Wickham, Rohit Prajapati, Brett B Finlay, Philip M. ShermanAbstract:Abstract Verotoxin-Producing Escherichia Coli (VTEC) O157:H7 inhibits interferon-γ-stimulated tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1 in epithelial cells, independent of Verotoxins and the locus of enterocyte effacement pathogenicity island. Although E. Coli O157:H7 is the major cause of disease in humans, non-O157:H7 VTEC also cause human disease. However, the virulence properties of non-O157:H7 VTEC are less well characterized. The aims of this study were to define the ability of VTEC strains of differing seropathotypes (classified as A–E) to inhibit interferon-γ stimulated Stat1-phosphorylation and to further characterize the bacterial-derived inhibitory factor. Confluent T84 and HEp-2 cells were infected with VTEC strains (MOI 100:1, 6 h, 37 °C), and then stimulated with interferon-γ (50 ng/mL) for 0.5 h at 37 °C. Whole-cell protein extracts of infected cells were collected and prepared for immunoblotting to detect tyrosine phosphorylation of Stat1. The effects of E. Coli O55 strains, the evolutionary precursors of VTEC, on Stat1-tyrosine phosphorylation were also determined. The effects of isogenic mutants of O-islands 47 and 122 were tested to determine the role of genes encoded on these putative pathogenicity islands in mediating VTEC inhibition of the interferon-γ-Stat1 signaling cascade. To evaluate potential mechanism(s) of inhibition, VTEC O157:H7-infected cells were treated with pharmacological inhibitors, including, wortmannin and LY294002. Relative to uninfected cells, Stat1-tyrosine phosphorylation was significantly reduced after 6 h infection of both T84 and HEp-2 cells by VTEC strains of all five seropathotypes. E. Coli O55 strains, but not enteropathogenic E. Coli (EPEC), also caused inhibition of Stat1-tyrosine phosphorylation, suggesting that this effect was acquired early in the evolution of VTEC. Stat1-activation did not recover in epithelial cells infected with isogenic mutants of O-islands 47 and 122, indicating that the inhibitory factor was not contained in these genomic regions. Stat1-phosphorylation remained intact when VTEC-infected cells were treated with wortmannin (0–100 nM), but not by treatment with the more specific PI3-kinase inhibitor, LY294002. Inhibition of interferon-γ stimulated Stat1-tyrosine phosphorylation by VTEC of multiple seropathotypes indicates the presence of a common inhibitory factor that is independent of bacterial virulence in humans. The results of treatment with wortmannin suggest that the bacterial-derived inhibitory factor employs host cell signal transduction to mediate inhibition of Stat1-activation.
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Multiple seropathotypes of Verotoxin-Producing Escherichia Coli (VTEC) disrupt interferon-gamma-induced tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1.
Microbial pathogenesis, 2006Co-Authors: Narveen Jandu, Mohamed A. Karmali, Songhai Shen, Mark E Wickham, Rohit Prajapati, Brett B Finlay, Philip M. ShermanAbstract:Verotoxin-Producing Escherichia Coli (VTEC) O157:H7 inhibits interferon-gamma-stimulated tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1 in epithelial cells, independent of Verotoxins and the locus of enterocyte effacement pathogenicity island. Although E. Coli O157:H7 is the major cause of disease in humans, non-O157:H7 VTEC also cause human disease. However, the virulence properties of non-O157:H7 VTEC are less well characterized. The aims of this study were to define the ability of VTEC strains of differing seropathotypes (classified as A-E) to inhibit interferon-gamma stimulated Stat1-phosphorylation and to further characterize the bacterial-derived inhibitory factor. Confluent T84 and HEp-2 cells were infected with VTEC strains (MOI 100:1, 6h, 37 degrees C), and then stimulated with interferon-gamma (50 ng/mL) for 0.5h at 37 degrees C. Whole-cell protein extracts of infected cells were collected and prepared for immunoblotting to detect tyrosine phosphorylation of Stat1. The effects of E. Coli O55 strains, the evolutionary precursors of VTEC, on Stat1-tyrosine phosphorylation were also determined. The effects of isogenic mutants of O-islands 47 and 122 were tested to determine the role of genes encoded on these putative pathogenicity islands in mediating VTEC inhibition of the interferon-gamma-Stat1 signaling cascade. To evaluate potential mechanism(s) of inhibition, VTEC O157:H7-infected cells were treated with pharmacological inhibitors, including, wortmannin and LY294002. Relative to uninfected cells, Stat1-tyrosine phosphorylation was significantly reduced after 6h infection of both T84 and HEp-2 cells by VTEC strains of all five seropathotypes. E. Coli O55 strains, but not enteropathogenic E. Coli (EPEC), also caused inhibition of Stat1-tyrosine phosphorylation, suggesting that this effect was acquired early in the evolution of VTEC. Stat1-activation did not recover in epithelial cells infected with isogenic mutants of O-islands 47 and 122, indicating that the inhibitory factor was not contained in these genomic regions. Stat1-phosphorylation remained intact when VTEC-infected cells were treated with wortmannin (0-100 nM), but not by treatment with the more specific PI3-kinase inhibitor, LY294002. Inhibition of interferon-gamma stimulated Stat1-tyrosine phosphorylation by VTEC of multiple seropathotypes indicates the presence of a common inhibitory factor that is independent of bacterial virulence in humans. The results of treatment with wortmannin suggest that the bacterial-derived inhibitory factor employs host cell signal transduction to mediate inhibition of Stat1-activation.
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Translocation of verotoxin-1 across T84 monolayers: mechanism of bacterial toxin penetration of epithelium
American Journal of Physiology-gastrointestinal and Liver Physiology, 1997Co-Authors: Dana J. Philpott, Mohamed A. Karmali, Cameron A. Ackerley, Amanda J. Kiliaan, Mary H. Perdue, Philip M. ShermanAbstract:Verotoxin-Producing Escherichia Coli (VTEC) are pathogenic bacteria associated with diarrhea, hemorrhagic Colitis, and hemolytic uremic syndrome. Verotoxins (VTs) elaborated by these organisms prod...
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Multiple determinants of Verotoxin-Producing Escherichia Coli O157:H7 attachment-effacement.
Infection and Immunity, 1993Co-Authors: M. Dytoc, Rohini Soni, F Cockerill, J. C. S. De Azavedo, M. Louie, James Brunton, Philip M. ShermanAbstract:Abstract Verotoxin-Producing Escherichia Coli strains of the serotype O157:H7 belong to a class of gastrointestinal pathogens that adhere to epithelial cells in a characteristic pattern known as attaching and effacing. Recent insight into the nature of E. Coli O157:H7 adhesion was provided by the cloning and sequencing of the chromosomal eaeA (for E. Coli attaching and effacing) gene homolog (G. Beebakhee, M. Louie, J. De Azavedo, and J. Brunton, FEMS Microbiol. Lett. 91:63-68, 1992, and J. Yu and J. B. Kaper, Mol. Microbiol. 6:411-417, 1992) and isolation of a 60-MDa plasmid referred to as pO157 (I. Toth, M. L. Cohen, H. S. Rumschlag, L. W. Riley, E. H. White, J. H. Carr, W. W. Bond, and I. K. Wachsmuth, Infect. Immun. 58:1223-1231, 1990, and S. Tzipori, H. Karch, K. I. Wachsmuth, R. M. Robins-Browne, A. D. O'Brien, H. Lior, M. L. Cohen, J. Smithers, and M. M. Levine, Infect. Immun. 55:3117-3125, 1987) and an approximately 94-kDa outer membrane protein (94-kDa OMP; P. Sherman, F. Cockerill III, R. Soni, and J. Brunton, Infect. Immun. 59:890-899, 1991). In this study, we examined the gene products of both eaeA and pO157 in relation to the 94-kDa OMP and as candidate effectors for O157:H7 attachment-effacement. Peptide sequencing and immunoassay demonstrated that the C. Coli O157:H7 eaeA gene product is distinct from the 94-kDa OMP. Using ultrastructural analyses, we found that both parent and pO157 plasmid-cured O157:H7 strains demonstrated attaching and effacing adhesion to host epithelial cells and reacted equally well to rabbit antiserum raised against the 94-kDa OMP. By both transmission electron microscopy and light microscopy, E. Coli HB101 transformed separately with the cloned eaeA gene and the pO157 plasmid did not form attaching and effacing lesions on cultured epithelial cells in vitro and rabbit intestinal tissues in vivo. Since additional determinants may mediate the attaching and effacing phenotype, we examined transposon TnphoA mutants constructed from E. Coli O157:H7 strain CL8. Two TnphoA mutants were found deficient in bacterial factors that are necessary for O157:H7 attachment-effacement and likely distinct from the eaeA gene product.
Carlton L. Gyles - One of the best experts on this subject based on the ideXlab platform.
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Production of Verotoxin and Distribution of O Islands 122 and 43/48 among Verotoxin-Producing Escherichia Coli O103:H2 Isolates from Cattle and Humans
Applied and Environmental Microbiology, 2008Co-Authors: Musafiri Karama, Roger P. Johnson, Robert Holtslander, Carlton L. GylesAbstract:This study investigated variations in the occurrence of markers of O islands 122 and 43/48 and in verotoxin 1 production in 91 Verotoxin-Producing Escherichia Coli (VTEC) O103:H2 strains of bovine and human origins. None of the genes that were investigated appear to be virulence indicators for human O103:H2 VTEC.
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Phenotypic and Genotypic Characterization of Verotoxin-Producing Escherichia Coli O103:H2 Isolates from Cattle and Humans
Journal of Clinical Microbiology, 2008Co-Authors: Musafiri Karama, Roger P. Johnson, Robert Holtslander, Carlton L. GylesAbstract:Characterization of important non-O157 Verotoxin-Producing Escherichia Coli (VTEC) has lagged considerably behind that of O157:H7 strains. This study characterized 91 VTEC O103:H2 strains from bovine and human sources and of North American and European origins by virulence or putative virulence genes, pulsed-field gel electrophoresis (PFGE) patterns, plasmid profiles, antimicrobial resistance, and Colicin production. All strains were positive for vt1 and eae-; 97% were positive for ehxA; and all were negative for hlyA. Two strains carried vt2. There were 66 PFGE patterns grouped in six clusters, and there were 25 different plasmid profiles. Plasmid-encoded katP and etp genes were significantly more frequent in European than in North American human strains. The distribution of selected phenotypes was as follows: enterohemorrhagic E. Coli (EHEC) hemolysin, 95%; Colicin production, 38%; antimicrobial resistance, 58%. All the strains were negative for the alpha-hemolytic phenotype. In conclusion, the VTEC O103:H2 strains were diverse, as shown by PFGE, plasmid profiles, virulence markers, and antimicrobial resistance patterns, and all strains showed an EHEC hemolytic phenotype instead of the alpha-hemolytic phenotype that has been shown previously. Verotoxin-Producing Escherichia Coli (VTEC) strains, also termed Shiga toxin-producing E. Coli strains, are important food-borne pathogens that have been associated with outbreaks of diarrhea and hemorrhagic Colitis, which may lead to life-threatening complications such as the hemolytic-uremic syndrome (HUS) in humans (27). More than 500 VTEC sero
J. Bouvet - One of the best experts on this subject based on the ideXlab platform.
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Effects of slaughter processes on pig carcass contamination by Verotoxin-Producing Escherichia Coli and E. Coli O157:H7.
International journal of food microbiology, 2002Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, V Atrache, C Vernozy-rozandAbstract:The aims of the present study were: (i) to evaluate Verotoxin-Producing Escherichia Coli (VTEC) faecal carriage of slaughtered pigs; (ii) to determine the effects of three different pig slaughtering processes on pig carcass contamination by VTEC; (iii) to characterise the VTEC strains isolated from pig and pig slaughterhouses (virulence genes and serotype); and (iv) to compare the strains isolated in the same slaughterhouse in order to identify the routes of contamination inside the slaughterhouse. Pork carcasses from three French slaughterhouses were sampled at three steps of the slaughter process and different sites in each slaughterhouse were sampled at three different times in the work day. Faecal material from each sampled carcass, potable water and scalding water were also collected. Detection of stx genes was performed by polymerase chain reaction (PCR) on a total of 1227 samples. In addition, a second PCR specific for E. Coli O157:H7 detection was carried out on the stx-positive samples. VTEC strains were recovered from positive samples by colony hybridisation or immunoconcentration, then serotyped, genetically characterised (eae, ehx, stx1, stx2, stx2c, uidA genes associated with virulence) and pulsotyped. No E. Coli O157:H7 was isolated from the three uidA-positive samples. VTEC faecal carriage was 31%. Global carcass contamination decreased with slaughter process (from 46% to 15%), whereas environmental contamination increased (from 7% to 29%). No VTEC isolates harboured eae, ehx, and uidA genes. VTEC contamination routes were not clearly identified.
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Effects of cutting process on pork meat contamination by Verotoxin-Producing Escherichia Coli (VTEC) and E. Coli O157:H7.
International journal of food microbiology, 2002Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, V Atrache, C Vernozy-rozandAbstract:The aims of the present study were: (i) to evaluate Verotoxin-Producing Escherichia Coli (VTEC) prevalence in pork cutting meat; (ii) to determine the effects of cutting process on pork meat contamination by VTEC; (iii) to characterise the VTEC strains isolated from pork and pork cutting plants (virulence genes and serotype); and (iv) to compare the strains isolated the same day in the same cutting plant in order to identify the routes of contamination inside the cutting plant. Pork carcasses from three French cutting plants were sampled before carcass cutting (carcass samples), after carcasses were divided into big portions (untrimmed cuts) and after preparation of primal cuts (rindless boneless cuts), and different environmental sites in each cutting plant were sampled at three different times in the work day. Potable water was also collected. PCR detection of stx genes was performed on a total of 2042 samples. In addition, a second PCR specific for E. Coli O157:H7 detection was carried out on the stx-positive samples. VTEC strains were recovered from positive samples by colony hybridisation or immunoconcentration, then serotyped, genetically characterised (eae, ehx, stx1, stx2, stx2e, uidA and genes which are associated with virulence) and pulsotyped. No E. Coli O157:H7 was detected. Meat contamination decreased from carcass (12%) and primary cuts (19%) to secondary cuts (5%), whereas environmental contamination increased after 2 h of activity (from 3% before the commencement of the work day to 25% and 20%, 2 and 6 h after commencement of cutting). No VTEC isolates harboured eae, ehx and uidA genes. VTEC contamination routes were not clearly identified.
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Effects of slaughter processes on pig carcass contamination by Verotoxin-Producing Escherichia Coli and E. Coli O157:H7.
International Journal of Food Microbiology, 2002Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, V Atrache, Christine Vernozy-rozandAbstract:Abstract The aims of the present study were: (i) to evaluate Verotoxin-Producing Escherichia Coli (VTEC) faecal carriage of slaughtered pigs; (ii) to determine the effects of three different pig slaughtering processes on pig carcass contamination by VTEC; (iii) to characterise the VTEC strains isolated from pig and pig slaughterhouses (virulence genes and serotype); and (iv) to compare the strains isolated in the same slaughterhouse in order to identify the routes of contamination inside the slaughterhouse. Pork carcasses from three French slaughterhouses were sampled at three steps of the slaughter process and different sites in each slaughterhouse were sampled at three different times in the work day. Faecal material from each sampled carcass, potable water and scalding water were also collected. Detection of stx genes was performed by polymerase chain reaction (PCR) on a total of 1227 samples. In addition, a second PCR specific for E. Coli O157:H7 detection was carried out on the stx-positive samples. VTEC strains were recovered from positive samples by colony hybridisation or immunoconcentration, then serotyped, genetically characterised (eae, ehx, stx1, stx2, stx2e, uidA genes associated with virulence) and pulsotyped. No E. Coli O157:H7 was isolated from the three uidA-positive samples. VTEC faecal carriage was 31%. Global carcass contamination decreased with slaughter process (from 46% to 15%), whereas environmental contamination increased (from 7% to 29%). No VTEC isolates harboured eae, ehx, and uidA genes. VTEC contamination routes were not clearly identified.
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Prevalence of Verotoxin-Producing Escherichia Coli and E. Coli O157:H7 in pig carcasses from three French slaughterhouses.
International journal of food microbiology, 2001Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, C Arquillière, Christine Vernozy-rozandAbstract:Verotoxin-Producing Escherichia Coli (VTEC) are important food-borne pathogens in humans. Several studies have demonstrated that cattle are a major reservoir of VTEC but few data are available about the occurrence of VTEC in other species. In France, there is no data about pigs and pork meat. The main purpose of this study was to evaluate the prevalence of E. Coli O157:H7 and other VTEC in pork carcasses. The second aim of the study was to get a picture of pork carcass contamination by VTEC. Pork carcasses from three French slaughterhouses (50 carcasses per slaughterhouse) were tested for the presence of VTEC and E. Coli O157:H7. For each carcass, both internal and external sites were investigated (five on pig skin and three on muscles) and samples were collected by cutting out a surface of 25 cm2. A total of 1200 samples were analyzed by the polymerase chain reaction (PCR) after an enrichment step. Primers used were degenerate-sequences which allowed amplification of various types of verotoxin genes (stx). In addition, a second PCR which specifically detected E. Coli O157:H7 was carried out on the stx-positive samples. The percentage of stx-positive PCR samples and carcasses was 12.7% (152/1200) and 50% (75/150), respectively. No E. Coli O157:H7 was detected. The prevalence for each slaughterhouse was not significantly different. Skin samples of belly, leg and shoulder allowed detection of more than 80% of the VTEC positive carcasses.
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Detection of Verotoxin-Producing Escherichia Coli (VTEC) in pig samples (faeces, carcass, slaughterhouse and cutting plant) using PCR
2001Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, Christine Vernozy-rozandAbstract:SUMMARY Verotoxin-Producing Escherichia Coli (VTEC) are important food-borne pathogens in humans. Several studies have demonstrated that cattle are a major reservoir of VTEC but few data are available about the occurrence of VTEC in other animals. In France, there is no data about pigs and pork meat. The purpose of this work was to develop a PCR-based method for detection of VTEC in different pig samples (meat, pig skin, carcass swab, environmental swab, faecal samples and scalding water). All VTEC strains were detected by PCR procedure. Shigella dysenteriae type 1 was the only other bacterium that gave positive result in this assay. For the 4 serotypes tested detection was possible up to a contamination rate before enrichment of 10 cfu per sample. The results indicate that this method is applicable for the detection of VTEC in pig slaughterhouse and cutting plant.
Mohamed A. Karmali - One of the best experts on this subject based on the ideXlab platform.
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Multiple seropathotypes of Verotoxin-Producing Escherichia Coli (VTEC) disrupt interferon-γ-induced tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1
Microbial Pathogenesis, 2007Co-Authors: Narveen Jandu, Mohamed A. Karmali, Songhai Shen, Mark E Wickham, Rohit Prajapati, Brett B Finlay, Philip M. ShermanAbstract:Abstract Verotoxin-Producing Escherichia Coli (VTEC) O157:H7 inhibits interferon-γ-stimulated tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1 in epithelial cells, independent of Verotoxins and the locus of enterocyte effacement pathogenicity island. Although E. Coli O157:H7 is the major cause of disease in humans, non-O157:H7 VTEC also cause human disease. However, the virulence properties of non-O157:H7 VTEC are less well characterized. The aims of this study were to define the ability of VTEC strains of differing seropathotypes (classified as A–E) to inhibit interferon-γ stimulated Stat1-phosphorylation and to further characterize the bacterial-derived inhibitory factor. Confluent T84 and HEp-2 cells were infected with VTEC strains (MOI 100:1, 6 h, 37 °C), and then stimulated with interferon-γ (50 ng/mL) for 0.5 h at 37 °C. Whole-cell protein extracts of infected cells were collected and prepared for immunoblotting to detect tyrosine phosphorylation of Stat1. The effects of E. Coli O55 strains, the evolutionary precursors of VTEC, on Stat1-tyrosine phosphorylation were also determined. The effects of isogenic mutants of O-islands 47 and 122 were tested to determine the role of genes encoded on these putative pathogenicity islands in mediating VTEC inhibition of the interferon-γ-Stat1 signaling cascade. To evaluate potential mechanism(s) of inhibition, VTEC O157:H7-infected cells were treated with pharmacological inhibitors, including, wortmannin and LY294002. Relative to uninfected cells, Stat1-tyrosine phosphorylation was significantly reduced after 6 h infection of both T84 and HEp-2 cells by VTEC strains of all five seropathotypes. E. Coli O55 strains, but not enteropathogenic E. Coli (EPEC), also caused inhibition of Stat1-tyrosine phosphorylation, suggesting that this effect was acquired early in the evolution of VTEC. Stat1-activation did not recover in epithelial cells infected with isogenic mutants of O-islands 47 and 122, indicating that the inhibitory factor was not contained in these genomic regions. Stat1-phosphorylation remained intact when VTEC-infected cells were treated with wortmannin (0–100 nM), but not by treatment with the more specific PI3-kinase inhibitor, LY294002. Inhibition of interferon-γ stimulated Stat1-tyrosine phosphorylation by VTEC of multiple seropathotypes indicates the presence of a common inhibitory factor that is independent of bacterial virulence in humans. The results of treatment with wortmannin suggest that the bacterial-derived inhibitory factor employs host cell signal transduction to mediate inhibition of Stat1-activation.
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Multiple seropathotypes of Verotoxin-Producing Escherichia Coli (VTEC) disrupt interferon-gamma-induced tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1.
Microbial pathogenesis, 2006Co-Authors: Narveen Jandu, Mohamed A. Karmali, Songhai Shen, Mark E Wickham, Rohit Prajapati, Brett B Finlay, Philip M. ShermanAbstract:Verotoxin-Producing Escherichia Coli (VTEC) O157:H7 inhibits interferon-gamma-stimulated tyrosine phosphorylation of signal transducer and activator of transcription (Stat)-1 in epithelial cells, independent of Verotoxins and the locus of enterocyte effacement pathogenicity island. Although E. Coli O157:H7 is the major cause of disease in humans, non-O157:H7 VTEC also cause human disease. However, the virulence properties of non-O157:H7 VTEC are less well characterized. The aims of this study were to define the ability of VTEC strains of differing seropathotypes (classified as A-E) to inhibit interferon-gamma stimulated Stat1-phosphorylation and to further characterize the bacterial-derived inhibitory factor. Confluent T84 and HEp-2 cells were infected with VTEC strains (MOI 100:1, 6h, 37 degrees C), and then stimulated with interferon-gamma (50 ng/mL) for 0.5h at 37 degrees C. Whole-cell protein extracts of infected cells were collected and prepared for immunoblotting to detect tyrosine phosphorylation of Stat1. The effects of E. Coli O55 strains, the evolutionary precursors of VTEC, on Stat1-tyrosine phosphorylation were also determined. The effects of isogenic mutants of O-islands 47 and 122 were tested to determine the role of genes encoded on these putative pathogenicity islands in mediating VTEC inhibition of the interferon-gamma-Stat1 signaling cascade. To evaluate potential mechanism(s) of inhibition, VTEC O157:H7-infected cells were treated with pharmacological inhibitors, including, wortmannin and LY294002. Relative to uninfected cells, Stat1-tyrosine phosphorylation was significantly reduced after 6h infection of both T84 and HEp-2 cells by VTEC strains of all five seropathotypes. E. Coli O55 strains, but not enteropathogenic E. Coli (EPEC), also caused inhibition of Stat1-tyrosine phosphorylation, suggesting that this effect was acquired early in the evolution of VTEC. Stat1-activation did not recover in epithelial cells infected with isogenic mutants of O-islands 47 and 122, indicating that the inhibitory factor was not contained in these genomic regions. Stat1-phosphorylation remained intact when VTEC-infected cells were treated with wortmannin (0-100 nM), but not by treatment with the more specific PI3-kinase inhibitor, LY294002. Inhibition of interferon-gamma stimulated Stat1-tyrosine phosphorylation by VTEC of multiple seropathotypes indicates the presence of a common inhibitory factor that is independent of bacterial virulence in humans. The results of treatment with wortmannin suggest that the bacterial-derived inhibitory factor employs host cell signal transduction to mediate inhibition of Stat1-activation.
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The Association Between Idiopathic Hemolytic Uremic Syndrome and Infection by Verotoxin-Producing Escherichia Coli
The Journal of Infectious Diseases, 2004Co-Authors: Mohamed A. Karmali, Martin Petric, Peter C. Fleming, Gerald S. Arbus, H. LiorAbstract:Forty pediatric patients with idiopathic hemolytic uremic syndrome (HUS) were investigated for evidence of infection by Verotoxin-Producing Escherichia Coli (VTEC). Fecal VTEC (belonging to at least six different O serogroups including 026, 0111, 0113, 0121, 0145, and 0157) or specifically neutralizable free-fecal Verotoxin (VT) or both were detected in 24 (60%) patients but were not detected in 40 matched controls. Ten of 15 of the former developed fourfold or greater rises in VT-neutralizing antibody titers, as did six other patients who were negative for both fecal VTEC and VT. A total of 30 (75%) patients had evidence of VTEC infection by one or more criteria. We concluded that a significant association exists between idiopathic HUS and infection by VTEC. The detection of free-fecal VT was the most important procedure for the early diagnosis of this infection because, in our study, VTEC were never isolated in the absence of fecal VT, whereas fecal VT was often present even when VTEC were undetectable.
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Translocation of verotoxin-1 across T84 monolayers: mechanism of bacterial toxin penetration of epithelium
American Journal of Physiology-gastrointestinal and Liver Physiology, 1997Co-Authors: Dana J. Philpott, Mohamed A. Karmali, Cameron A. Ackerley, Amanda J. Kiliaan, Mary H. Perdue, Philip M. ShermanAbstract:Verotoxin-Producing Escherichia Coli (VTEC) are pathogenic bacteria associated with diarrhea, hemorrhagic Colitis, and hemolytic uremic syndrome. Verotoxins (VTs) elaborated by these organisms prod...
Christine Vernozy-rozand - One of the best experts on this subject based on the ideXlab platform.
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Effects of slaughter processes on pig carcass contamination by Verotoxin-Producing Escherichia Coli and E. Coli O157:H7.
International Journal of Food Microbiology, 2002Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, V Atrache, Christine Vernozy-rozandAbstract:Abstract The aims of the present study were: (i) to evaluate Verotoxin-Producing Escherichia Coli (VTEC) faecal carriage of slaughtered pigs; (ii) to determine the effects of three different pig slaughtering processes on pig carcass contamination by VTEC; (iii) to characterise the VTEC strains isolated from pig and pig slaughterhouses (virulence genes and serotype); and (iv) to compare the strains isolated in the same slaughterhouse in order to identify the routes of contamination inside the slaughterhouse. Pork carcasses from three French slaughterhouses were sampled at three steps of the slaughter process and different sites in each slaughterhouse were sampled at three different times in the work day. Faecal material from each sampled carcass, potable water and scalding water were also collected. Detection of stx genes was performed by polymerase chain reaction (PCR) on a total of 1227 samples. In addition, a second PCR specific for E. Coli O157:H7 detection was carried out on the stx-positive samples. VTEC strains were recovered from positive samples by colony hybridisation or immunoconcentration, then serotyped, genetically characterised (eae, ehx, stx1, stx2, stx2e, uidA genes associated with virulence) and pulsotyped. No E. Coli O157:H7 was isolated from the three uidA-positive samples. VTEC faecal carriage was 31%. Global carcass contamination decreased with slaughter process (from 46% to 15%), whereas environmental contamination increased (from 7% to 29%). No VTEC isolates harboured eae, ehx, and uidA genes. VTEC contamination routes were not clearly identified.
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Prevalence of Verotoxin-Producing Escherichia Coli and E. Coli O157:H7 in pig carcasses from three French slaughterhouses.
International journal of food microbiology, 2001Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, A Le Roux, M P Montet, C Arquillière, Christine Vernozy-rozandAbstract:Verotoxin-Producing Escherichia Coli (VTEC) are important food-borne pathogens in humans. Several studies have demonstrated that cattle are a major reservoir of VTEC but few data are available about the occurrence of VTEC in other species. In France, there is no data about pigs and pork meat. The main purpose of this study was to evaluate the prevalence of E. Coli O157:H7 and other VTEC in pork carcasses. The second aim of the study was to get a picture of pork carcass contamination by VTEC. Pork carcasses from three French slaughterhouses (50 carcasses per slaughterhouse) were tested for the presence of VTEC and E. Coli O157:H7. For each carcass, both internal and external sites were investigated (five on pig skin and three on muscles) and samples were collected by cutting out a surface of 25 cm2. A total of 1200 samples were analyzed by the polymerase chain reaction (PCR) after an enrichment step. Primers used were degenerate-sequences which allowed amplification of various types of verotoxin genes (stx). In addition, a second PCR which specifically detected E. Coli O157:H7 was carried out on the stx-positive samples. The percentage of stx-positive PCR samples and carcasses was 12.7% (152/1200) and 50% (75/150), respectively. No E. Coli O157:H7 was detected. The prevalence for each slaughterhouse was not significantly different. Skin samples of belly, leg and shoulder allowed detection of more than 80% of the VTEC positive carcasses.
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Detection of Verotoxin-Producing Escherichia Coli (VTEC) in pig samples (faeces, carcass, slaughterhouse and cutting plant) using PCR
2001Co-Authors: J. Bouvet, R. Rossel, C. Bavai, S. Ray-gueniot, C. Mazuy, Christine Vernozy-rozandAbstract:SUMMARY Verotoxin-Producing Escherichia Coli (VTEC) are important food-borne pathogens in humans. Several studies have demonstrated that cattle are a major reservoir of VTEC but few data are available about the occurrence of VTEC in other animals. In France, there is no data about pigs and pork meat. The purpose of this work was to develop a PCR-based method for detection of VTEC in different pig samples (meat, pig skin, carcass swab, environmental swab, faecal samples and scalding water). All VTEC strains were detected by PCR procedure. Shigella dysenteriae type 1 was the only other bacterium that gave positive result in this assay. For the 4 serotypes tested detection was possible up to a contamination rate before enrichment of 10 cfu per sample. The results indicate that this method is applicable for the detection of VTEC in pig slaughterhouse and cutting plant.
